This invention relates to a boat lift and, in particular, to a hydraulically operated boat lift for raising a boat out of the water.
Many boaters wish to dock their boats out of the water in order to reduce the amount of waterborne contamination that might collect upon the hull. Keeping the vessel out of the water when not in use also helps to preserve components from damage and deterioration caused by water. In addition, the craft can be more easily repaired and maintained when raised well clear of the water. Furthermore, in certain geographic locales that experience relatively mild winters, the lift can remain in the water year round and can be used to store the boat during the winter months.
As described by Hey in U.S. Pat. No. 5,908,264, many boat lifts currently in use include a main frame that is supported beneath the surface of the water upon legs or the like. A pair of spaced apart parallel bunk rails are mounted upon the frame by lifting arms so that rails can be raised by hydraulic cylinders from a home or boat receiving position beneath the water to an elevated or raised position wherein the boat is lifted free of the water. Although this type of lifting device works well in practice, it has one drawback in that the parallel bunk rails generally do not conform to the various and diverse shapes of many boat hulls and, as a consequence, the boat being serviced by the lift can be seated in the bunk rails in a potentially unstable condition. In addition, because the bunk rails are located beneath the water when in the lowered or boat receiving position, it is oftentimes difficult for the boat operator to guide the boat properly onto the bunk rails.
It is, therefore, an object of the present invention to improve apparatus for lifting boats out of the water.
It is a further object of the present invention to more securely support a water craft upon the bunk rails of a hydraulic or pneumatic boat lift.
A still further object of the present invention is to provide the bunk rails of a boat lift with sufficient adjustability such that the rails can be set to better conform to the shape of a boat""s hull.
Another object of the present invention is to simplify the guiding and aligning of a boat onto the bunk rails of a boat lift.
Yet another object of the present invention is to improve the safety of hydraulic and pneumatic boat lifts.
These and other objects of the present invention are attained by a boat lift that includes a rectangular-shaped stationary frame that is supported by legs beneath the surface of a body of water. A rectangular-shaped lifting frame having spaced apart front and rear laterally disposed cross members is mounted over the stationary frame. The lifting frame is connected to the stationary frame by lifting arms which guide the lifting frame between a first lowered boat receiving position beneath the water and a second raised position wherein the boat is elevated out of the water. Hydraulic or pneumatic cylinders are employed to raise and lower the lifting frame. A pair of bunk rails are mounted upon the cross members of the lifting frame by adjustable retainers for locating each bunk rail independently upon the cross member and thus to allow the rails to be positioned in close conformity with the shape of a hull. A pair of raised guide rails are also adjustably mounted upon the lifting frame so that the guide rails extend upwardly above the surface of the water when the lifting frame is in the lowered or boat receiving position and serves to help the boat operator guide the boat onto the bunk rails.